Abstract: An apparatus for controlling the exhaust timing of a two-cycle engine. A control valve is provided for adjusting the position of the top of the control port in the two-cycle engine as a function of the engine speed. A central processing unit receives a signal from an engine speed detector indicating the engine's operating speed. Based upon a control map, the central processing unit initiates action to adjust the position of the control valve.

Abstract: An exhaust timing controller for controlling an exhaust timing member in a two cycle engine including a control circuit for generating a control signal which actuates a mechanism for moving the exhaust timing member. The control circuit controls the member such that the member is drivable in a range from a fully open position to a fully closed position responsive to certain engine conditions including engine speed and rate of change of engine speed. A self cleaning cycle is provided which drives the exhaust timing member first to one position limit and then to the other.

Abstract: An exhaust timing controller for controlling an exhaust timing member in a two cycle engine includes a control circuit for generating a control signal which actuates a mechanism for moving the exhaust timing member. The control circuit controls the member such that the member is drivable in a range from a fully open position to a fully closed position responsive to certain engine conditions including engine speed. A self cleaning cycle is provided which drives the exhaust timing member first to one position limit and then to the other. This may be performed with initial operation of the engine above a specified engine speed with the position of the exhaust timing member being independent of engine speed during cleaning.